At least another 100 people will be charged for their part in the Capitol riot, according to new legal filings.
More than 300 people already face prosecution for the violence that unfolded in Washington DC on 6 January, in which five people died.
Federal prosecutors say they now have more than 15,000 hours of surveillance and body camera video turned over by 14 law enforcement agencies.
They also revealed that they have carried out 900 search warrants in all 50 states, have examined 1,600 electronic devices, and are reviewing more than 210,000 tips and 80,000 witness interviews.
Prosecutors say the scope of the investigation means they will likely have to use outside vendors to sort the evidence and set up a review system agreed upon by lawyers on both sides of the probe.
They have now started to file 60-day delays in the cases of the pro-Trump defendants because of the volume of evidence to go through, reported Politico.
“The investigation and prosecution of the Capitol Attack will likely be one of the largest in American history, both in terms of the number of defendants prosecuted and the nature and volume of the evidence,” wrote US attorneys in a filing lodged on Friday morning in the cases of nine alleged Oath Keepers.
“Over 300 individuals have been charged in connection with the Capitol attack. The investigation continues and the government expects that at least one hundred additional individuals will be charged.”
Supporters of the ex-president stormed the US Capitol to prevent the certification of Joe Biden’s election victory, following a “Stop the Steal” rally for Mr Trump.
The ex-president was impeached for a historic second time in the House for his role, although he was later acquitted in the Senate when not enough Republicans voted against him.
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